The Lepontine dome or Lepontin dome is a region of tectonic uplift

Tectonic uplift

Tectonic uplift is a geological process most often caused by plate tectonics which increases elevation. The opposite of uplift is subsidence, which results in a decrease in elevation. Uplift may be orogenic or isostatic.-Orogenic uplift:...

 in the Swiss

Switzerland

Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....

 part of the Alps

Alps

The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....

. It is located in the Lepontine Alps

Lepontine Alps

The Lepontine Alps are a mountain range in the central part of the Alps. They are located in Switzerland and Italy .On the north the upper Rhône valley separate them from the Bernese Alps and the Furka Pass and the upper Reuss valley separates them from the Urner Alps; on the west the Simplon Pass...

 and Glarus Alps

Glarus Alps

The Glarus Alps are a mountain range in central Switzerland. They extend from the Oberalp Pass to the Klausen Pass, and are bordered by the Urner Alps to the west, the Lepontine Alps to the south and the Appenzell Alps to the northeast...

.

The Alps north of the Periadriatic Seam

Periadriatic Seam

The Periadriatic Seam is a distinct geologic fault in Southern Europe, running S-shaped about 1000 km from the Tyrrhenian Sea through the whole Southern Alps as far as Hungary. It forms the division between the Adriatic plate and the European plate...

 are usually divided into three large nappe

Nappe

In geology, a nappe is a large sheetlike body of rock that has been moved more than or 5 km from its original position. Nappes form during continental plate collisions, when folds are sheared so much that they fold back over on themselves and break apart. The resulting structure is a...

 complexes. From bottom to top these are the Helvetic

Helvetic nappes

The Helvetic zone, Helvetic system or the Helveticum is a geologic subdivision of the Alps. The Helvetic zone crops out mainly in Switzerland, hence the name . Rocks in the Helvetic zone are sedimentary and were originally deposited at the southern margin of the European plate...

, Penninic

Penninic nappes

The Penninic nappes or the Penninicum are one of three nappe stacks and geological zones in which the Alps can be divided. In the western Alps the Penninic nappes are more obviously present than in the eastern Alps , where they crop out as a narrow band...

 and Austroalpine nappes

Austroalpine nappes

The Austroalpine nappes are a geological nappe stack in the European Alps. The Alps contain three such stacks, of which the Austroalpine nappes are structurally on top of the other two...

. East of the dome all three are found on top of each other. The same counts for the region west of the dome, if the Sesia unit

Sesia unit

The Sesia unit or Sesia nappe, also called the Sesia-Dent Blanche unit is a tectonic unit or terrane in the Swiss and Italian Alps. The zone crops out in the Pennine Alps and in the southeastern part of the Aosta Valley...

 is seen as part of the Austroalpine nappes. The dome itself however only shows Penninic and Helvetic (the boundary between the two is still disputed) rocks. Apparently the uplift of the dome caused the upper Austroalpine material to be totally eroded

Erosion

Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...

 away.

The creation of the dome was caused by a phase of east-west directed extension in the Miocene

Miocene

The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...

 that occurred throughout the Eastern

Eastern Alps

Eastern Alps is the name given to the eastern half of the Alps, usually defined as the area east of the Splügen Pass in eastern Switzerland. North of the Splügen Pass, the Posterior Rhine forms the border, and south of the pass, the Liro river and Lake Como form the boundary line.-Geography:The...

 and Central Alps. This extensional phase was probably a result of slab detachment in the upper mantle

Mantle (geology)

The mantle is a part of a terrestrial planet or other rocky body large enough to have differentiation by density. The interior of the Earth, similar to the other terrestrial planets, is chemically divided into layers. The mantle is a highly viscous layer between the crust and the outer core....

. Similar large extensional structures appear in more places in the Alps, examples are the Hohe Tauern window

Hohe Tauern window

The Hohe Tauern window is a geological structure in the Austrian Central Eastern Alps. It is a window in the Austroalpine nappes where high-grade metamorphic rocks of the underlying Penninic nappes crop out...

 and the smaller Engadin and Rechnitz windows.